New Zoyi multimeter+oscilloscopes - ZT-70xS, up to 50MHz/250MSps (nov 2022)

[rsjsouza]

Mine arrived a bit earlier than expected, attached are some higher resolution teardown photos.

Thanks for sharing.

- It doesn't appear to be possible to disable the awful beep when switching functions

Common in Chinese meters. I dislike this as well.

- Large amount of trigger jitter on non-repetitive waveforms, such as a calibration time-marker signal of 2us/div or higher.

I wonder if the 702 does that as well.

- No mean voltage measurement function

This was also present in the 702 as well.

- The bayonet of multiple BNC connectors I tried wasn't able to be rotated all the way into the locked position

Too bad. Do the provided probes can be locked?

[ddrl46]

- The bayonet of multiple BNC connectors I tried wasn't able to be rotated all the way into the locked position

Too bad. Do the provided probes can be locked?

The supplied probes do sort of jam into place and do seem somewhat secure, however it doesn't appear that these lock properly either. It might be worth looking into longer BNC connectors to replace the supplied ones.

Here are some images of the unit displaying a 50 MHz sine wave. The unit is set to high-speed acquisition mode in order to maximize the sample rate. The signal appears quite unstable.


When decreasing the frequency slightly, in this case 46 MHz, the signal clears up quite a bit.

[rsjsouza]

A similar scenario, considering the paper bandwidth. My ZT702S (10MHz on paper) shows a very stable waveform at 1MHz, usable at 5MHz but at 10 it is quite jagged.

[ahakman]

Mine arrived a bit earlier than expected, attached are some higher resolution teardown photos.

Nice humble brag that shipping in and to the Netherlands is far superior than shipping in the US (color me NOT shocked!). Mine is still somewhere between here and Shenzen   

[Veteran68]

Mine arrived a bit earlier than expected, attached are some higher resolution teardown photos.

Mine is still somewhere between here and Shenzen   

If you ordered from the same AliExpress Snakol store as the rest of us, you should have tracking that shows you where it is. Mine was in-state yesterday and should arrive by tomorrow.

[kwass]

Got mine today, firmware version 1.0.9, so many bugs!

The multimeter functions well, is very accurate and seems bug free other than it switches back to Volts DC when you change from scope mode to DMM.  (The ZT-702 remembers the DMM settings.) It does not have a temperature measurement like the ZT-702 does but it have one interesting new feature -- you can set it to output a 115.2kb UART ASCII description of the currently displayed reading on the scope probe calibration lug!

The scope works well to 25Mhz at least, 50 Mhz is defiantly pushing it.  Cursors are now available and work ok but reset when you leave scope mode and come back in.  X-Y mode works but updates are painfully slow.  You can choose to show up to 4 measurements per channel from the list (VPP, Vmax, Vmin, RMS, Duty, Prd, Freq and Fcnt -- seems to be trigger counts).

The signal generator is just awful:  No amplitude setting, hard to change frequency, incredibly noisy, very limited range.  It outputs on the probe calibration lug but turns off the scope function when running.  You can output some of the signal generator options on the calibration lug when the scope is running using another menu option (Output Setting).  I have no idea why these are not combined.  On the positive side, the function generator is under a menu setting called "More Apps" along with and imgView app (let's you see screen shots you've saved).  Maybe there's more stuff to come.


Some of the bugs:

- Sometimes it gets into modes that limit the range of the time base, using the "default" setting option fixes this.
- I see crazy results for Fcnt and sometimes for Freq on measurements.
- Power on always goes into scope mode.
- Attempting to set the signal generator below 4Hz crashes the instrument!

I sure hope that they have new firmware in the works!

[ahakman]

If you ordered from the same AliExpress Snakol store as the rest of us, you should have tracking that shows you where it is. Mine was in-state yesterday and should arrive by tomorrow.

I did order from the Snakol store (it's the only store on Ali that seems to have it so far). I also ordered 3 other items on AliExpress the day prior that all arrived today, but the ZT703s still shows "Arrived at Linehaul office" on the same day as "departed from departure country / region" yesterday, so I'm not even sure it's on the boat yet... it must've slept in and missed the boat everyone else's meter got on.

[Veteran68]

Mine arrived yesterday as expected.

As noted by others, even though a recent FW update for the 702S remembers the last used mode (DMM or Scope), the 703S once again defaults to scope mode at powerup. Not a huge deal for me as this will be seldom used as a DMM considering how many others I have, but odd that they regressed the functionality in this newer model.

[ahakman]

I expect new firmware will be released at some point. If you read back a couple of pages, someone that is getting sent a "review unit" said they indicated they knew there were firmware bugs and will release new versions at some point.

I really wish they'd just make the firmware open source - all the bugs would be fixed, and every last ounce of additional features possible would be added before the 100th unit got delivered!

I bet the firmware is similar to, but not exactly the same as the ZT702S - the one guy looking after it hasn't yet ported the diffs from the 702 firmware to the 703 firmware and recompiled it...

[Altair8800]

For reference/comparison,

Ordered ZT-703S w/2 probes from "SNAKOL Official Store" on AliExpress on 25 Dec 2023, arrived in USA on 5 Jan 2024.

[Randy222]

I too ordered the 703S from snakol, it shipped fast and is already in the air. I expect to get it faster than the ali tracking info says.

[ahakman]

My ZT703S finally arrived today.

One bug I found is with the frequency measurement when in "High" Run Mode is not accurate. I set the signal generator to 5khz sine (the max it goes to??). With measurements turned on on CH1, in "Normal" Run Mode, it shows the measured frequency at 5kHz, but in "High" run mode, it shows the frequency as 8.75kHz

Measuring with the cursors gives incorrect readings as well. In "High" mode, one cycle of the waveform measures as 114.3uS (~8.748kHz), and in normal mode one cycle of the signal measures as 200uS (5kHz).

I don't have another oscilloscope here to verify the output of the frequency generator in High vs Normal mode - maybe the bug is with the frequency generator in high mode, not the oscilloscope, and the scope is actually measuring correctly?? I could easily check if I was at home, but don't exactly have a lot of test equipment available while on vacation! I'm sure someone else could check this and see where the bug lies.

Also for a scope that's supposed to go to 50Mhz, the minimum timebase is 100us/div?? In the photos above from ddrl46, they have it in 10ns/div - mine says it's at a limit at 100us/div?? Edited: Oh, I see now, if the function generator is on anything other than probe calibrator output (square wave 1kHz), the minimum timebase is limited to 100us/div, but if you put the function generator to square wave 1kHz, then the timebase can go down to 10ns/div - RTFM!!

Another bug is triggering doesn't work properly at 100ns/div. Trigger on the probe compensation signal, start at 10ns/div and go up...
10ns, 25ns, 50ns all trigger correctly, 100ns doesn't (trigger is somewhere off the left edge of the screen), 250ns, 500ns, 1us, etc etc all trigger correctly again.

Definitely some bugs in the first firmware!

On the multimeter side, the continuity beeper is latching and quite quick, and the resistance autoranging seems ok-ish (about 2S to range from OL to low ohms shorting the probes together). Both issues that I think people were complaining about on the ZT702.

Sort of a minor thing, but I skimmed the manual too, and was quite surprised that the English is actually pretty good - it was definitely edited by someone that's a native English speaker, or at least a very good English speaker. There's only one or 2 instances of some odd phrasing - not even bad enough to call them Chinglish.

They definitely put some effort into this thing!

[evmillan]

I’ve ordered the ZT-703S with 2 probes from "SNAKOL Official Store" on AliExpress on 27 Dec 2023, arrived to Spain on 5 Jan 2024.

[Altair8800]

My ZT703S finally arrived today.

One bug I found is with the frequency measurement when in "High" Run Mode is not accurate. I set the signal generator to 5khz sine (the max it goes to??). With measurements turned on on CH1, in "Normal" Run Mode, it shows the measured frequency at 5kHz, but in "High" run mode, it shows the frequency as 8.75kHz

Measuring with the cursors gives incorrect readings as well. In "High" mode, one cycle of the waveform measures as 114.3uS (~8.748kHz), and in normal mode one cycle of the signal measures as 200uS (5kHz).

I don't have another oscilloscope here to verify the output of the frequency generator in High vs Normal mode - maybe the bug is with the frequency generator in high mode, not the oscilloscope, and the scope is actually measuring correctly?? I could easily check if I was at home, but don't exactly have a lot of test equipment available while on vacation! I'm sure someone else could check this and see where the bug lies.

It might not be a bug (or a feature  ) it might just be the way the ZT-703S Oscilloscope works.  The manual on page 19 says the following...

=====
* Run Mode:
The oscilloscope is equipped with two operating modes:  Normal mode and High-Speed mode.  Enter the forth menu, press F3 to toggle between them.  Depending on the measurement signal, if the input signal is less than 30MHz, it is recommended to use Normal mode.  If the measurement signal frequency is higher than 30MHz, it is advisable to switch to High-Speed mode.

Normal Mode:  Maximum sampling rate 200MSa/s, Maximum measurement bandwidth 30MHz;  Lower power consumption, more power-efficient.

High-Speed Mode; Maximum sampling rate 280MSa/s, Maximum measurement bandwidth 50MHz, Higher power consumption.
=====

The manual kind of hints not to use High Speed Mode under 30MHz. 

Maybe they could reword it better to say something like
...it is recommended to use Normal mode to get more accurate results...

I assume there is some overlap like High-Speed Mode is accurate at say above 20MHz or 10MHz, but you tested at more than an order of magnitude lower at 8.75kHz so [I assume] it is just outside the range of accuracy for High-Speed Mode.

Note:  This is my first scope, I cannot test this hypothesis (maybe others).  I'm not a scope aficionado or expert...

[kwass]

In high speed mode, the cursors problem is caused because the scope changes the virtual, horizontal graticule without modifying the cursor positions.   I think that changing the graticule spacing is the bug here, why are they doing that?

High speed mode does indeed improve the waveform display accuracy at higher frequencies at the expense of a minor increase in current draw from the battery, but I found that it only adds about 20ma

[ahakman]

I have a feeling the bug is that in High mode, the firmware doesn't compensate for the higher sampling rate of the ADC, and then everything is wrong - the graticle, the cursors, and the measurements.

It's definitely not a "feature" - regardless of operating mode, a scope should never show the wrong frequency when displaying measurements.
As I said though, without another scope, I can't tell if the bug is in the function generator, or in the scope part, but it sounds like it's in the scope part. If I was at home, I'd be able to verify that in 30 seconds, both by measuring the output of the function generator, as well as feeding in a signal from an external function generator and verifying the measurement on another scope.

[Altair8800]

FYI:  The English Manual PDF for the ZT-703S Zoyi/Zotek Oscilloscope&DMM can be found here:

https://zotektools.com/products/zoyi-zt-703s/

Then scroll down and click "Download User Manual"

OR direct link from Dropbox here:
https://www.dropbox.com/scl/fi/qm8vlwby6lqrolhy36m8r/ZT-703S-EN.pdf?rlkey=iaqfg4i1jcn2gumccvhv6msx7&dl=0


Whenever I get a new product I like to snag a PDF copy of the manual... Easier to find and easier to search...

[gtv]

I have a feeling the bug is that in High mode, the firmware doesn't compensate for the higher sampling rate of the ADC, and then everything is wrong - the graticle, the cursors, and the measurements.

It's definitely not a "feature" - regardless of operating mode, a scope should never show the wrong frequency when displaying measurements.
As I said though, without another scope, I can't tell if the bug is in the function generator, or in the scope part, but it sounds like it's in the scope part. If I was at home, I'd be able to verify that in 30 seconds, both by measuring the output of the function generator, as well as feeding in a signal from an external function generator and verifying the measurement on another scope.

I received my Zoyi 703s yesterday. And I checked the high-speed mode of the Zoyi with the generator of my Hantek2D72. At 5kHz and 2.5 volts. Zoyi displays the same thing in both modes: 5.2kHz. This leads to the conclusion that the fault lies in the Zoyi's generator. But it took me a lot longer than 30 seconds, I had to search and unpack my Hantek first  Maybe someone can check this additionally?

[gtv]

Ahakman: Another bug is triggering doesn't work properly at 100ns/div. Trigger on the probe compensation signal, start at 10ns/div and go up...
10ns, 25ns, 50ns all trigger correctly, 100ns doesn't (trigger is somewhere off the left edge of the screen), 250ns, 500ns, 1us, etc etc all trigger correctly again.

I tried that too, but didn't notice any problems at 100ns. Also tried with 1kHz probe compensation. But what I noticed is that when the autotrigger is triggered with DC input, the amplitude of the square wave signal goes above the screen. Below the center line the signal is displayed correctly. If you set the input to AC, it triggers correctly.

[winkot]

The ZT-702S oscilloscope does not show the end of charging on the display. The battery icon does not change. How to determine that charging has ended?

[Randy222]

The ZT-702S oscilloscope does not show the end of charging on the display. The battery icon does not change. How to determine that charging has ended?

Buy a 703S ? 

Crappy firmware.

My 703S should arrive tomorrow, so I get to try it then.

[winkot]

Buy a 703S ?

With even more crooked firmware? 

[ahakman]

Ahakman: Another bug is triggering doesn't work properly at 100ns/div. Trigger on the probe compensation signal, start at 10ns/div and go up...
10ns, 25ns, 50ns all trigger correctly, 100ns doesn't (trigger is somewhere off the left edge of the screen), 250ns, 500ns, 1us, etc etc all trigger correctly again.

I tried that too, but didn't notice any problems at 100ns. Also tried with 1kHz probe compensation. But what I noticed is that when the autotrigger is triggered with DC input, the amplitude of the square wave signal goes above the screen. Below the center line the signal is displayed correctly. If you set the input to AC, it triggers correctly.

I wasn't in auto trigger - I had manually set a trigger level, and then stepped through the timebase settings, and it doesn't trigger correctly at 100ns/div at all (or at least the trigger point is way off the screen somewhere).
I just took screenshots at a bunch of time bases, and interestingly, the screenshot at 100ns/div is also corrupted in a weird way.

You can see at all other timebases, the edge is in the middle of the display where it should be, but at 100ns/div, the edge is somewhere off the screen entirely.

There's definitely a bug there.

[ahakman]

The ZT-702S oscilloscope does not show the end of charging on the display. The battery icon does not change. How to determine that charging has ended?

On the ZT-703S, the icon flashes between the charging icon and the full battery icon when it's full.

Maybe that indicates it's intermittently charging the battery even though it's full - probably not good for the battery.
I wouldn't leave it plugged in for long times when the battery is full if it's continually trying to charge it "a little more".

[gtv]

I also have the 100ns error in manual trigger mode. Thanks Ahakman, great series of pictures, I get the same results. In high speed mode the following result occurs, a flickering correct result....